| transient retinopathy | Transient traumatic retinal angiopathy due to a sudden rise in venous pressure, as in compression of the body from seat belt injury; ocular fundi show large white patches associated with the retinal veins about the disk or macula, haemorrhages, and retinal oedema; thought to be due to fat embolism from bone marrow. Synonym: Purtscher's disease, transient retinopathy, traumatic retinopathy. (05 Mar 2000) |
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| epidemic transient diaphragmatic spasm | An acute infectious disease usually occurring in epidemic form, characterised by paroxysms of pain, usually in the chest, and associated with strains of Enterovirus coxsackievirus type B. Synonym: benign dry pleurisy, Bornholm disease, Daae's disease, devil's grip, diaphragmatic pleurisy, epidemic benign dry pleurisy, epidemic diaphragmatic pleurisy, epidemic myalgia, epidemic myositis, myositis epidemica acuta, epidemic transient diaphragmatic spasm, Sylvest's disease. (05 Mar 2000) |
| all-trans-retinal | The orange retinaldehyde resulting from the action of light on the rhodopsin of the retina, which converts the 11-cis-retinal component of the rhodopsin to all-trans-retinal plus opsin. Synonym: trans-retinal, visual yellow. (05 Mar 2000) |
| blood-retinal barrier | Specialised nonfenestrated tightly-joined endothelial cells that form a transport barrier for certain substances between the retinal capillaries and the retinal tissue. (12 Dec 1998) |
| central retinal fovea | A depression in the centre of the macula retinae containing only cones and lacking blood vessels. Synonym: fovea centralis retinae, central pit. (05 Mar 2000) |
| retinal | 1. <anatomy> Pertaining to the retina. 2. <biochemistry> The aldehyde of retinol, derived by the oxidative enzymatic splitting of absorbed dietary carotene and having vitamin A activity. In the retina, retinal combines with opsins to form visual pigments. One isomer, 11 cis retinal combines with opsin in the rods (scotopsin) to form rhodopsin or visual purple. Another, all trans retinal (trans r.), visual yellow, xanthopsin) results from the bleaching of rhodopsin by light, in which the 11 cis form is converted to the all trans form. Retinal also combines with opsins in the cones (photopsins) to form the three pigments responsible for colour vision. (18 Nov 1997) |
| retinal adaptation | Adjustment to degree of illumination. (05 Mar 2000) |
| retinal anlage tumour | A benign neoplasm of neuroectodermal origin that most often involves the anterior maxilla of infants in the first year of life. It presents clinically as a rapidly growing blue-black lesion producing a destructive radiolucency; histologically, it is characterised by small round undifferentiated tumour cells interspersed with larger polyhedral melanin-producing cells arranged in an alveolar configuration. Synonym: melanoameloblastoma, pigmented ameloblastoma, pigmented epulis, progonoma of jaw, retinal anlage tumour. (05 Mar 2000) |
| retinal blood vessels | The blood vasculature of the retina, including the branches and tributaries of the central retinal artery and vein, respectively, and the vascular circle of the optic nerve. Synonym: vasa sanguinea retinae. (05 Mar 2000) |
| retinal camera | An instrument for photographing the ocular fundus. (05 Mar 2000) |
| retinal cone | <ophthalmology, physiology> One of the two photoreceptor cell types in the vertebrate retina. In cones the photopigment is in invaginations of the cell membrane of the outer segment. Cones are less sensitive to light than rods, and are differentially sensitive to particular wavelengths of light and therefore important for colour vision. They provide vision with higher spatial and temporal acuity, and it is the combination of signals from cones with different pigments that facilitates colour vision. There are three types of cones, each type sensitive to red, green or blue. Present in large numbers in the fovea. (03 Jul 1999) |
| retinal degeneration | <ophthalmology> A retrogressive pathological change in the retina, focal or generalised, caused by genetic defects, inflammation, trauma, vascular disease, or aging. Degeneration affecting predominantly the macula lutea of the retina is macular degeneration. (03 Jul 1999) |
| retinal dehydrogenase | An oxidoreductase catalyzing the interconversion of retinaldehyde and NAD+ to retinoic acid and NADH; thus affecting growth and differentiation. Synonym: retinaldehyde dehydrogenase. (05 Mar 2000) |
| retinal detachment | <ophthalmology> A painless disorder (when spontaneous) where the patient complains of a gradual raising or lowering of a curtain over the visual field of the affected eye. May also occur as the result of trauma. (27 Sep 1997) |
| retinal disease | <ophthalmology> A general term which describes any retinal changes (haemorrhages or exudates) that can affect vision (for example diabetic retinopathy, hypertensive retinopathy). (27 Sep 1997) |